Aside from his loyalty to Father and disgust for children, Pierre is shown to take great pride in his culinary work, particularly in the giant cake that he and his men prepared for Father. Because of this, he is easily irritated by Father letting his flames melt the cake, claiming it was his "crea-tion" (putting emphasis on the second syllable).
Operation: C.A.K.E.D.-F.I.V.E. was his first and only appearance, making him more or less a background character.
Later when Sector V arrives to rescue them, Numbuh 3 distracts the entire ice cream men staff by inviting them to a party on Cell Block. She tells him that he's not on her list of invitees - this is the last time he has any lines, nor does he have any cameo appearances in other episodes.